Graphene’s exceptional thermal properties have driven various studies on its use as a filler in thermal interface materials. Recent work on thermal interface materials (TIMs) has primarily focused on curing composites which dry to solid, such as epoxy. For various applications in electronics, non-curing grease-like, i.e. soft, TIMs are needed.

The era of big data has increased the need to find optimal ways of transferring heat out of the electronic component. Current commercially available TIMs perform in a range of 0.5 W/mK to 5 W/mK, which no longer meets the industry’s demands. The thrust for better performing non-curing TIMs motivated the studies on the enhancement of thermal properties with the addition of graphene fillers into commercially available non-curing TIMs.

The first studies of graphene composites found that even small loading fractions of randomly oriented graphene fillers – up to f=10 vol.% – can increase the thermal conductivity of epoxy composites by up to a factor of ×25. In this
work, we investigated the high loading fractions of graphene fillers into a base matrix of mineral oil for electronic applications, with a loading fraction surpassing 50%. The intrinsic thermal conductivity of large graphene layers exceeds that of the high-quality bulk graphite, which by itself is very high – 2,000W/mK near room temperature (RT) [9] .

In this sense, graphene is an ideal filler material. Recent progress in liquid phase exfoliation of graphene and graphene oxide reduction allow for mass production of graphene at low cost. We show that our non-curing TIMs with graphene, prepared without extra processing steps or filler functionalization, can surpass in their performance the currently available commercial TIMs.